Semiconductor carrier with vertical power fet module

ABSTRACT

A monolithic power switch provides a semiconductor layer, a three dimensional FET formed in the semiconductor layer to modulate currents through the semiconductor layer, and a toroidal inductor with a ceramic magnetic core formed on the semiconductor layer around the FET and having a first winding connected to the FET.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplications numbered 60/358,040, filed Jun. 24, 2010 and 61/059,391,filed Jun. 28, 2010 and incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

The present invention generally relates to DC/DC power managementdevices configured as a fully integrated system on a semiconductor layeras a monolithic structure that modulates the power drawn through thelayer with a vertical FET switch and a diode embedded in thesemiconductor layer surface, and more specifically to the integration ofsuch a device in a semiconductor carrier that has other circuitrysatisfying critical performance tolerances integrated within it and isused to supply power to and maintain electrical communication betweenone or more semiconductor integrated circuits attached to thesemiconductor carrier surface.

BACKGROUND OF THE INVENTION

DC/DC power management systems generally regulate static orswitched-mode DC power levels supplied at a particular voltage/current.Static power management systems condition the output voltage and currentto levels that are appropriate for a particular circuit. When operatedin a switched-mode, these power management systems are also used tocycle power within a given circuit at time periods that cause thecircuit to “turn off” during time intervals when its functions are notabsolutely needed by the larger system it serves. Power cycling isparticularly important in mobile systems to extend battery life, andwhen refreshing and clocking data between random access memory andmicroprocessor systems, particularly in multi-core microprocessorarchitectures. The concepts presented herein are not limited to DC/DCpower systems, and can be similarly applied to AC/DC inverter and AC/ACtransformer circuitry with rudimentary understanding of those skilled inthe art of power management.

Multi-processor core systems have particular relevance to the presentinvention. Localized high-speed computing systems co-locatemicroprocessor, memory, and micro-controller subsystem functions withina processing cell that is wired in parallel with other processor cells.Until recently, higher computing speeds are achieved by distributinginstructions across all the cells to allow each cell to worksimultaneously on an instruction packet. Fundamental limitationsrelating to the stability of the clock circuitry that times datatransfers within and between each of the subsystems, and the speed andpower levels at which external power management circuitry can supplypower to the computing cell is now causing the microprocessor to beunderutilized. These fundamental limitations now cause themicroprocessor of a single cell to operate at 25%-30% of its utilizationcapacity. Utilization capacities are further reduced whenmicroprocessors are arrayed in parallel. For instance, a 16 coremicroprocessor array will function slower than a 4 core microprocessorarray. The under-utilization of localized microprocessor arrays hasmotivated the development of cloud computing architectures thatdistribute computational functions across a computer network, which openundesirable risks to data security in many computational applications.Therefore, it is desirable to provide switched-mode power levels athigher speeds, as well as stable clock circuitry to a single processoror a multi-core processor system.

Thermal management considerations are a principal impediment toachieving these objectives. Power management systems and processor coresgenerate heat that compromises performance when not adequately managed.The significant heat generated in power management circuitry having lessthan optimal efficiencies cause it to be physically isolated, typicallyon another board, from memory, microprocessor, controller circuitry,which generate large amounts of heat in their own right. The physicalseparation contributes to the less than optimal delivery of power at thespeeds necessary to resolve these problems. Methods that produce higherefficiency power management modules which generate lower heat levelspermit higher power levels to be supplied by placing the powermanagement device in closer proximity to memory and microprocessor corecircuitry. Co-location of high efficiency switched-mode power managementdevices with one or more processor cells also reduce overall systempower losses through much shorter interconnect circuitry. Methods andapparatus that improve supplied power to a processor core are thereforedesirable to the enhanced utilization of microprocessor arrays and theimproved operational efficiency of high-speed computing systems.

Heat generated by the processor circuitry and any co-located powermanagement device alters the timing of conventional clock circuitry.This causes a need for additional control circuitry to maintain stableclock functionality. Therefore, the development of clock circuitry thatremains stable with varying temperature, and the introduction ofadditional means to reduce the power consumed by semiconductor die inelectrical communication with co-located power management systems arealso desirable.

DESCRIPTION OF THE PRIOR ART

Hopper et al., U.S. Pat. No. 7,652,348 B1, “APPARATUS & METHOD FOR WAFERLEVEL FABRICATION OF HIGH VALUE INDUCTORS ON SEMICONDUCTOR IC's”, issuedJan. 1, 26, 2010, teach the assembly of inductor coils on semiconductorwafers containing active devices buried beneath the wafer surface usinghigh permeability magnetic core material prepared from powder pastes.

Bose et al., U.S. Ser. No. 12/023,536, “METHOD AND SYSTEMS OF MULTI-COREMICROPROCESSOR POWER MANAGEMENT AND CONTROL VIA PER-CHIPLET PROGRAMMABLEPOWER MODES”, filed Jan. 31, 2008, published Aug. 6, 2009, as U.S. Pub.No. 2009/0199020 A1, instructs a system that manages power in amicroprocessor core and an associated memory cache.

Ewing et al., U.S. Ser. No. 12/344,419, “POWER DISTRIBUTION, MANAGEMENT,AND MONITORING SYSTEMS AND METHODS”, filed Dec. 26, 2008, and publishedSep. 17, 2009 as U.S. Pub. No. 2009/0234512 discloses the discreteassembly of a power management system that contains toroidal inductorcoils.

Hughes et al., U.S. Ser. No. 12/356,624, “PROCESSOR POWER MANAGEMENT ANDMETHOD”, filed Jan. 21, 2009, and published Jul. 22, 2010 as U.S. Pub.No. 2010/0185820 A1, induces a sequence of sleep modes among multipleprocessors cores to optimize power utilization in under-utilizedmulti-core processor configurations (Hughes et al. '624).

Finkelstein et al., U.S. Ser. No. 12/263,421, “POWER MANAGEMENT FORMULTIPLE PROCESSOR CORES”, filed Oct. 31, 2008, and published May 6,2010, as U.S. Pub. No. 2010/0115304 A1, instructs techniques to managepower consumption locally in processor and the distribution of poweramong different power planes of a processor core based on energy-basedconsiderations.

Yung-Hsiang, U.S. Ser. No. 11/713,889, “POWER MANAGEMENT IN COMPUTEROPERATING SYSTEMS”, filed Mar. 5, 2007, and published Oct. 18, 2007 asU.S. Pub. No. 2007/0245163 A1, instructs the use of selection policiesto manage power distribution to components in a computer system.

Brittain et al., U.S. Ser. No. 11/463,743, “SYSTEMS AND METHODS FORMEMORY POWER MANANGEMENT”, filed Aug. 10, 2006, and published Feb. 14,2008 as 2008/0040563 A1, instructs systems for determining specificpower consumption and usage levels in computer memory systems.

Borkar et al. U.S. Pat. No. 7,568,112, “POWER DELIVERY AND POWERMANAGEMENT OF MANY CORE PROCESSORS”, filed Sep. 9, 2005, uses multiplevoltage regulators that may be integrated within the die or packagedwith the die to manage power to a multi-microprocessor core system.

Ou, U.S. Ser. No. 10/236,700, “INDUCTOR FORMED ON A SILICON SUBSTRATEAND METHOD OF MANUFACTURING THE SAME”, filed Sep. 5, 2002 and publishedJul. 3, 2003 as U.S. Pub. No. 2003/0122647 teaches the integration ofinductor coils using methods that are compatible with CMOS semiconductorprocesses.

Evans et al., U.S. Pat. No. 5,543,773. “TRANSFORMERS AND COUPLEDINDUCTORS WITH OPTIMUM INTERLEAVING”, issued Aug. 6, 1996, discloses thediscrete assembly of toroidal inductor and transformer coils on aprinted circuit board with optimal interleaving to minimize flux leakageand proximity losses as shown in FIG. 2.

DEFINITION OF TERMS

The term “active component” is herein understood to refer to itsconventional definition as an element of an electrical circuit that thatdoes require electrical power to operate and is capable of producingpower gain.

The term “amorphous material” is herein understood to mean a materialthat does not comprise a periodic lattice of atomic elements, or lacksmid-range (over distances of 10's of nanometers) to long-rangecrystalline order (over distances of 100's of nanometers).

The terms “chemical complexity”, “compositional complexity”, “chemicallycomplex”, or “compositionally complex” are herein understood to refer toa material, such as a metal or superalloy, compound semiconductor, orceramic that consists of three (3) or more elements from the periodictable.

The term “chip carrier” is herein understood to refer to an interconnectstructure built into a semiconductor substrate that contains wiringelements and active components that route electrical signals between oneor more integrated circuits mounted on chip carrier's surface and alarger electrical system that they may be connected to.

The term “DDMOSFET” herein references its conventional meaning as adouble-diffused dopant profile in conjunction with a field-effecttransistor that uses a metal-oxide-semiconductor interface to modulatecurrents.

The terms “discrete assembly” or “discretely assembled” is hereinunderstood to mean the serial construction of an embodiment through theassembly of a plurality of pre-fabricated components that individuallycomprise a discrete element of the final assembly.

The term “emf” is herein understood to mean its conventional definitionas being an electromotive force.

The term “EMI” is herein understood to mean its conventional definitionas electromagnetic interference.

The term “IGBT” herein references its conventional meaning as aninsulated gate bipolar transistor.

The term “integrated circuit” is herein understood to mean asemiconductor chip into which a large, very large, or ultra-large numberof transistor elements have been embedded.

The term “LCD” is herein understood to mean a method that uses liquidprecursor solutions to fabricate materials of arbitrary compositional orchemical complexity as an amorphous laminate or free-standing body or asa crystalline laminate or free-standing body that has atomic-scalechemical uniformity and a microstructure that is controllable down tonanoscale dimensions.

The term “liquid precursor solution” is herein understood to mean asolution of hydrocarbon molecules that also contains solublemetalorganic compounds that may or may not be organic acid salts of thehydrocarbon molecules into which they are dissolved.

The term “microstructure” is herein understood to define the elementalcomposition and physical size of crystalline grains forming a materialsubstance.

The term “MISFET” is herein understood to mean its conventionaldefinition by referencing a metal-insulator-semiconductor field effecttransistor.

The term “mismatched materials” is herein understood to define twomaterials that have dissimilar crystalline lattice structure, or latticeconstants that differ by 5% or more, and/or thermal coefficients ofexpansion that differ by 10% or more.

The term “MOSFET” is herein understood to mean its conventionaldefinition by referencing a metal-oxide-silicon field effect transistor.

The term “nanoscale” is herein understood to define physical dimensionsmeasured in lengths ranging from 1 nanometer (nm) to 100's of nanometers(nm).

The term “passive component” is herein understood to refer to itsconventional definition as an element of an electrical circuit that thatdoes not require electrical power to operate and is not capable ofproducing power gain.

The term “power FET” is herein understood to refer to the generallyaccepted definition for a large signal vertically configured MOSFET andcovers multi-channel (MUCHFET), V-groove MOSFET, truncated V-grooveMOSFET, double-diffusion DMOSFET, modulation-doped transistors (MODFET),heterojunction transistors (HETFET), and insulated-gate bipolartransistors (IGBT).

The term “standard operating temperatures” is herein understood to meanthe range of temperatures between −40° C. and +125° C.

The term “surface FET” is herein understood to understood by itsconventional definition as a field effect transistor that useselectrodes applied to, and electronic dopant profiles patterned on thesurface of and within a semiconductor layer to modulate current flowsacross the surface of the semiconductor layer.

The terms “tight tolerance” or “critical tolerance” are hereinunderstood to mean a performance value, such as a capacitance,inductance, or resistance, that varies less than ±1% over standardoperating temperatures.

In view of the above discussion, it would be beneficial to improve theoperational efficiency of semiconductor die, including the utilizationof processor cores, by shrinking their size, power consumption, usingmethods that enable reduced transistor counts, stable clock circuitry,and the delivery of higher power levels using high-frequency switchedmode power. The present invention instructs the monolithic integrationof low-loss high-power, high-speed switched-mode power management on asilicon carrier to improve the operational efficiency of semiconductordie, including processor cells, co-located on the silicon carrier.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a monolithic powerswitch, comprising: a semiconductor layer; a three dimensional FETformed in the semiconductor layer to modulate currents through thesemiconductor layer; and a toroidal inductor with a ceramic magneticcore formed on the semiconductor layer around the FET and having a firstwinding connected to the FET.

The switch may further comprise a semiconductor carrier having theswitch formed therein. The semiconductor carrier may include passiveceramic components formed thereon and electrically connected to theswitch. The switch may further comprising: a diode formed in thesemiconductor layer peripherally to the toroidal inductor and connectedto rectify current from the inductor; and a capacitor having a ceramicdielectric formed on the semiconductor layer, and connected to thediode.

The switch may further comprise a timing oscillator formed on thecarrier and comprising an oscillator coil formed on an amorphous silicalayer, wherein the oscillator coil holds its inductance value to within1% over a standard operating temperature range. The timing oscillatormay include switching elements formed in the carrier for controllingoscillation frequency of the oscillator coil.

The FET may be a double-diffused MOSFET or an insulated gate bipolartransistor. The FET may include a gate electrode having a gate width togate length ratio that is equal to or exceeds 100, or alternatively 10⁶.The FET may includes an elongated gate electrode that forms a resonanttransmission line. The elongated gate electrode may meander over an areaof the substrate located within a central opening of the toroidalinductor. The elongated gate electrode may be insulated with amorphoussilica. The second electrode may be located over the elongated gateelectrode and insulated therefrom.

Another embodiment of the present invention provides a semiconductorpower switch, comprising: a planar first electrode; a first layer dopedsemiconductor material disposed on the first electrode that forms ohmiccontact with the planar first electrode; a second layer of dopedsemiconductor material disposed on the first layer that iselectronically patterned to form a double-diffused MOSFET; a secondelectrode disposed upon the second layer; an elongated gate electrodelocated to modulate current flow from the planar first electrode throughthe second layer to the second electrode and having a ratio of gatewidth to gate length that this greater than or equal to 100; wherein theelongated gate electrode forms a serpentine pattern over the secondlayer and is insulated from the second region and the second electrode;and wherein the elongated gate structure forms a transmission line thatis resonant at a predetermined power switching frequency.

The switch may further comprise a circuit module having the switch ofclaim 1 formed therein. The elongated gate electrode may meanderadjacent a contiguous surface area of the second layer to maximize gatewidth over that contiguous surface area. The first layer may be formedas a region of the substrate and the contiguous surface area issurrounded by a toroidal inductor having a ceramic core formed on thesubstrate. The elongated gate electrode may include adjacent parallelgate portions.

The double-diffused MOSFET may include a pair of parallel elongatedchannel regions located beneath the elongated gate electrode. Theelongated gate electrode may be meandered and has a gate width to gatelength ratio that is greater than or equal to 10⁶.

The first semiconductor layer may be doped to form an insulated gatebipolar transistor when making electrical contact with the secondsemiconductor layer.

Yet another embodiment of the present invention provides a monolithicpower management module, comprising: a semiconductor carrier; a threedimensional FET formed in the semiconductor carrier to modulate currentsthrough the semiconductor carrier; and a toroidal inductor with aceramic magnetic core formed on the semiconductor carrier around the FETand having a first winding connected to the FET. The module may furthercomprise a plurality of active components and passive ceramic componentsformed on or in the semiconductor carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustratively shown and described in referenceto the accompanying drawings, in which:

FIG. 1 is a representative circuit schematic for a DC-DC converter infly-back configuration;

FIG. 2 depicts a monolithic power management module containing a surfaceFET;

FIG. 3 illustrates a cross-sectional view of a low loss magnetic corematerial;

FIG. 4 illustrates mechanically reinforced inductor windings wrappedaround a magnetic core with an amorphous silica gap.

FIG. 5A is a cross-sectional view of a DDMOS vertical power FET.

FIG. 5B is a top view of monolithic power management module with DDMOSvertical power FET containing an elongated resonant gate.

FIG. 5C is a top perspective view of the elongated resonant gate on thesurface of the electronically patterned semiconductor layer.

FIG. 5D illustrates an equivalent circuit representation of atransmission line segment.

FIG. 5E is a cross-sectional view of an IGBT vertical power FET.

FIG. 6 contrasts the current carrying capabilities of various verticalpower FETs.

FIG. 7A shows a top perspective view of a monolithic power managementdevice containing a vertical power FET with an elongated resonant gate.

FIG. 7B is an alternative perspective view of a monolithic powermanagement device containing a vertical power FET with an elongatedresonant gate.

FIG. 7C is another alternative perspective view of a monolithic powermanagement device containing a vertical power FET with an elongatedresonant gate.

FIG. 7D is a top perspective view of additional circuitry contained in amonolithic power management device containing a vertical power FET withan elongated resonant gate.

FIG. 7E is an equivalent circuit diagram of the additional circuitrydepicted in FIG. 7D.

FIG. 8A illustrates the variation in the relative permittivity of aperovskite electroceramic as a function of temperature at various grainsizes.

FIG. 8B illustrates the variation in the relative permeability as afunction of temperature in a compositionally complex magnetic ferriteelectroceramic having varying chemical compositions.

FIG. 9 shows a top perspective view of a semiconductor chip carrier thathas a monolithic power management device and clock circuitry thatremains stable with temperature integrated on to its surface.

FIG. 10A illustrates a stochastic distribution in signal tuning causedby passive circuitry that has loose performance tolerances.

FIG. 10B depicts the redundant transistor banks that must be added to asemiconductor die to manage the stochastic distribution caused bypassive circuitry having loose tolerances.

FIG. 11A illustrates a stochastic distribution in signal tuningresulting from passive circuitry that satisfies critical performancetolerances.

FIG. 11B depicts the transistor banks needed for a semiconductor diethat is electrically interconnected with passive circuitry thatsatisfies critical performance tolerances.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is introduced using examples and particularembodiments for descriptive purposes. Although a variety of examples arepresented to show how various configurations can be employed to achievethe desired improvements, these particular embodiments are onlyillustrative and not intended in any way to restrict the inventionspresented.

This application is filed jointly with de Rochemont U.S. provisionalapplication number 61375894, “FULLY INTEGRATED HIGH POWER DENSITYSILICON CARRIER”, filed Aug. 23, 2010 (de Rochemont '894), which isincorporated herein by reference. The current application focusesprimarily on means to fully integrate a high efficiency, powermanagement system on a silicon carrier as a monolithic structure thatmodulates high current levels using a resonant gate structure enabled bya three-dimensional gate structure with serpentine windings. Thecounterpart application, (de Rochemont '894), addresses means to switchcurrent at high speed or over any desirable range of frequencies using aresonant transistor gate that has its resonance tuned through additionalpassive components inserted into the gate. The application is also filedjointly with de Rochemont U.S. provisional application No. 61/409,846,“QUANTUM DOT FIELD EFFECT TRANSISTOR IN A FULLY INTEGRATED SILICONCARRIER AND METHOD OF MANUFACTURE THEREOF”, filed Nov. 3, 2010 (deRochemont '846), which is incorporated herein by reference.

The current application incorporates by reference all matter containedin de Rochemont, U.S. Ser. No. 11/479,159, filed Jun. 30, 2006, entitled“ELECTRICAL COMPONENT AND METHOD OF MANUFACTURE” (the '159 application),de Rochemont, U.S. Ser. No. 11/620,042 filed Jan. 6, 2007 entitled“POWER MANAGEMENT MODULES” (the '042 application, de Rochemont andKovacs, U.S. Ser. No. 12/843,112 filed Jul. 26, 2010, “LIQUID CHEMICALDEPOSITION PROCESS APPARATUS AND EMBODIMENTS”, (the '112 application),and de Rochemont U.S. Ser. No. 13/152,222, entitled “MONOLITHIC DC/DCPOWER MANAGEMENT MODULE WITH SURFACE FET”, filed Jun. 2, 2011 (the '222application).

Reference is now made to FIGS. 1-4 to help illustrate certain aspects ofthis invention. FIG. 1 provides a circuit schematic of a DC/DC powermanagement system having fly-back configuration. A power managementsystem 1 is generally, but not necessarily, comprised of a DC powersource 3 that feeds at least one power switch 5, which modulates theprimary current 6 drawn from electrical ground to at least onetransformer 7 comprised of a primary inductor coil 9 and a secondaryinductor coil 11. Certain topologies may use an inductor coil 9,11 inseries or parallel connection as opposed to a transformer 7. In thefly-back configuration, the output of the primary coil current 6 inducesa back emf in the secondary coil that draws secondary current 13. Thesecondary coil 11 output current flows through a diode 15, whichsupplies the circuit's conditioned DC output power 16 and charges acapacitor 17 that supplies current to the secondary coil 11. A switchcontroller 19 monitors the differential output voltage 16, power sourcevoltage 3, and uses those inputs to modulate the power switch 5. Asnoted above, different power control circuit topologies will comprise atleast one switch 5, one diode 15, one capacitor 17, and one inductorcoil 9,11 or transformer coil 7, and one controller circuit 19. They mayadditionally comprise other passive (resistor, capacitor, and inductor)or active (diode or transistor switch) components not shown in FIG. 1that fall under the scope of the present invention.

FIG. 2 overviews a monolithic power management module 20 constructedusing the LCD methods taught in the '222 application by de Rochemont ona semiconductor layer 22 that functions as the fly-back power managementsystem 1 shown in FIG. 1. The power management module 20 modulatescurrent by a surface FET 24 integrated on the semiconductor layer 22that functions as the power switch 5. The surface FET 24 modulatescurrent from the DC power source 3 (FIG. 1) to the primary coil 9(FIG. 1) of a toroidal transformer coil 26. Current from the DC powersource 3 (FIG. 1) is supplied to the monolithic circuit from a backsideground contact 28 through a first ground pad 29 that is in electricalcommunications with the backside ground contact 28 through a via (notshown). An output pad 30 on the top surface of the semiconductor layer22 supplies conditioned DC output power 16 that has been regulated bythe monolithic DC-DC power management circuit 20. An embedded diode 32is circumferentially configured over part of the semiconductor surfacearea exterior to the toroidal transformer 26. The embedded diode 34 isin electrical communication with the output from secondary coil 11(FIG. 1) of the toroidal transformer 26, while the other is inelectrical communication with the output pad 30. On the opposite side ofthe toroidal transformer, a the bottom contact of a parallel platecapacitor 36 makes simultaneous electrical communication with a groundpad 38 located on the top surface of the semiconductor layer 22 and theinput of the secondary coil 11 of the toroidal transformer 26. Thecontrol circuitry 19 (FIG. 1) may be configured as a surface-mountedcontroller chip 40 as shown in FIG. 7, or it may alternatively beembedded in the semiconductor layer (not shown) if its semiconductormaterial is compatible with those functions. Power input to the circuitis supplied to the primary coil 9 of the toroidal transformer 26 throughan input pad 42. Additional circuitry 44 comprising active and passivecomponents may be added as needed between the first ground pad 29 andthe surface FET 24.

The toroidal transformer 26 minimizes EMI and current ripple in thepower management module 20 by providing a closed path for magneticcurrents circulating in the transformer structure and by forming asecondary inductor coil on the semiconductor layer that has its windingsprecisely interleaved between the windings of the primary inductor coilto mitigate flux leakage and proximity losses. High-frequency powerlosses in power management circuits are dominated by magnetic corelosses, power FET losses, and conductor loss. Conductor loss is relievedby shortening conductor lengths, which are minimized through monolithicintegration, and optimizing conductor geometry to a current'sfrequency-dependent skin depth. Hysteresis loss, eddy current, andresidual loss are the principal mechanisms for magnetic core losses. LCDmethods minimize hysteresis, eddy current, and residual magnetic loss inthe magnetic core 48 of the toroidal transformer 26, by integratingcompositionally complex high permeability magnetic core material,(μ_(r)≧10, preferably μ_(r)≧100) with the atomic scale chemicaluniformity fluctuating ≦1.5 mol %, which minimizes structural andcompositional defects that produce hysteresis losses. Eddy current andresidual losses are highly problematic in high-speed switched mode powersupplies operated at switching speeds greater than 10 MHz. A particularaspect of the invention reduces eddy current and residual losses in themagnetic core 48 of an inductor or transformer component to drive DC/DCpower management circuits at switching frequencies higher than 20 MHz,preferably frequencies higher than 500 MHz, while simultaneouslymanaging input/output currents≧10 A.

LCD methods are used to deposit compositionally complex amorphousmaterials having precise composition and atomic-scale elementaluniformity on arbitrary material layers as discussed in detail in deRochemont '159, de Rochemont '042, and de Rochemont and Kovacs '112,included herein by reference. This ability to selectively depositamorphous or uniformly crystalline deposits, permit the construction ofmonolithic structures on semiconductor layers having active componentsburied beneath its surface. LCD methods deposit oxide ceramics when thematerials are formed in oxygen atmospheres. Metals, alloys, superalloys,and semiconductors are integrated into the monolithic structures byprocessing the applied deposit in oxygen-free atmospheres.

A particular aspect of this invention address eddy current losses. Thefirst method utilizes LCD to add non-magnetic elements comprisingmagnesium oxide (MgO), zinc oxide (ZnO), and copper oxide (Cu) into themagnetic core material to increase its resistivity to levels greaterthan 10³ Ω-cm, preferably to levels greater than 10⁷ Ω-cm, whilesimultaneously holding the desired high permeability, μ_(R). The secondmethod shown in FIG. 3 optionally inserts at least one thin layer ofamorphous silica 50,50′ between layers of high resistivity, highpermeability ceramic material 51A,51B,51C within the magnetic core 52formed on the surface of a semiconductor layer. Amorphous silica is aformidable dielectric, endowed with a dielectric breakdown of 10,000KV-cm⁻¹ and an electrical resistivity on the order of 10¹⁶ Ω-cm, whilehaving low dielectric constant (∈_(R)=3.85) and low dielectric loss (tanδ=2×10⁻⁵). A principal objective of the amorphous silica layer(s) 50 incombination with the high-resistivity, high permeability ceramicmaterial 51 is to produce a magnetic core having an internal resistancegreater than 10⁵ Ω-cm⁻³ per Watt of acceptable loss at a given switchingfrequency. This level of internal resistance (ρ_(internal)) will reduceeddy current losses within the magnetic core to levels less than 0.5mW-cm⁻³, preferably to loss levels less than or equal to 20 μW-cm⁻³.These high internal resistance levels enable this aspect of theinvention to be applied to managing power levels of 500 W or more.Magnetic core materials are selected based upon the desired operationalswitching speed. Preferred electroceramic compositional families forvarious ranges of switching frequency for the intended application areshown in Table 1.

TABLE 1 Electroceramic Family Ferrite Hexaferrite Garnet Frequency ≦50MHz 20 to 3,000 MHz ≧1,000 MHz Range Compositional M₁Fe₂O₄ AB₁₂O₁₉A₃B₂(SiO₄)₃ Formula Elemental M = Co, Ni, Zn, A = Mg, Ca, Sr, A = Ca,Mg, Fe, Sr, Substitutes Cu, V, Mg, Li Ba, Sc, Cu, Zn Sc, Mn, Ba, Cu, ZnB = Fe, Bi, Y, Al B = Al, Fe, Bi, Cr, V, Zr, Ti, Si, Y, Co, Gd, Nd, HoCrystallographic Spinel, Body- Hexagonal Rhombic, Structure centeredcubic Dodecahedron or Trapezohedron

Yet another aspect of this invention applies the LCD process toformulate high permeability magnetic material having low residual loss,which is a dominant loss mechanism above 10 MHz. This aspect of theinvention utilizes LCD's ability to formulate a complex ceramiccomposition with uniform grain size diameter 53, wherein 100% of thegrains have diameters less than 1.5× the mean grain size diameter, andsaid grain mean size diameter less than 5 μm, preferably having grainsize in the range of 1 μm to 5 μm.

In high power density applications, the electromagnetic energy densityis sufficient to induce electromechanical forces that will mechanicallydisplace the coil windings at high power levels. This mechanicaldisplacement will destroy the equal spacing between primary andsecondary coil windings, which will induce proximity and flux leakagelosses, and could lead to catastrophic failure of the device. LCDmethods are used to mechanically reinforce windings against displacementand catastrophic failure as depicted in cross-section in FIG. 4. Themechanically reinforced transformer windings 60A,60B comprise thinlayers of high electrical conductivity material 61, preferably but notnecessarily copper conductor and might also comprise superconductingmaterial, that envelop a hard mechanical constraining member 62. Themechanical constraining member 62 may consist of a hard, low-expansionelemental metal, such as tungsten or molybdenum, or it may comprise analloy or superalloy, such as kovar, invar, or any other well-knownlow-expansion material that has a measured hardness value that is at aminimum twice (2×) the measured hardness value of the high electricalconductivity material 61. The thickness 63 of the high conductivitylayer 61 should range from 0.5× to 10× the ac skin depth at the device'soptimal operating or switching frequency. The coefficient of thermalexpansion (CTE) is a critical parameter in the selection of the hardmechanical constraining member 62, and should match to within 25%,preferably within 10% of the coefficient of thermal expansion of thedielectric material(s) with which the high electrical conductivitymaterial 61 is in physical contact. In designs where the high electricalconductivity material 61 is in contact with a plurality of adjacentdielectrics, such as the magnetic core 64 and an insulating dielectric65, it is preferred that the CTE of the hard mechanical constrainingmember 62 mechanically match the adjacent material 64,65 having thelower CTE. An additional aspect of the present invention uses amorphoussilica as the insulating dielectric 65 to prevent corona discharges (ordielectric breakdown if less strong insulators are used) betweenwindings of the primary and secondary coils. Amorphous silica is thelowest loss (tan δ=2×10⁻⁵) and most robust (threshold of dielectricbreakdown of 10,000 KV-cm⁻¹) dielectric insulator (≅10¹⁶ Ω-cm).

A further additional aspect of the present invention utilizes forms atoroidal magnetic core having gaps in the magnetic material that arefilled with an ultra-low loss material, preferably filled with amorphoussilica. It is well-known to practitioners skilled in the art oftransformer coil design that “air gaps” concentrate magnetic energy.Locating “air gaps” 66 in the magnetic core 64 to be adjacent to atleast one secondary coil winding 60B increases power coupling betweenthe primary coil 60A and secondary coil 60B windings.

Reference is now made FIGS. 5-8 to illustrate aspects of the inventionthat further improve the power and thermal efficiencies of a powermanagement module through the monolithic integration of a vertical powerFET to boost power (current) levels through the structure whileminimizing thermal loads. Insulating dielectric material 65 (FIG. 4)used to electrically isolate windings and traces, or as physical layersin the monolithic construction of the power management module, has beenremoved in most instances from FIGS. 5-8 for clarity.

FIGS. 5A,5B,5C,5D illustrate alternative structures to the monolithicpower management module 20 shown in FIG. 2 that improve management ofhigh current loads by utilizing a vertical power FET 100 in lieu of thesurface FET 24. The term “vertical power FET” is herein understood as afield effect transistor that uses electrodes applied to, and electronicdopant profiles patterned on the surface of and within one or moresemiconductor layers to modulate current drawn through the semiconductorlayer(s). FIG. 5A is a cross-sectional view of line segment A-A′ of themonolithic power management module with a vertical FET 150 depicted inFIG. 5B. The term “vertical power FET” refers to a field effecttransistor that uses electrodes applied to a semiconductor layer thathas electronic dopant profiles patterned on its surface and within oneor more semiconductor layers to modulate current drawn through thesemiconductor layer(s). The vertical power FET 100 draws current 102through a semi-insulating n-type semiconductor layer 104 from an n⁺-typesemiconductor drain layer 106. The semiconductor drain layer 106 may bea chip carrier substrate (discussed below) or an additionalsemiconductor layer deposited on a ground electrode 107. The activejunction that modulates the current drawn through this structure isformed by diffusing or implanting p-type dopants to form sub-channelregions 108 and n-type regions 110 to complete the NPN junctiontransistor circuit. Gate electrodes 112 are embedded in amorphous silicadielectric 114 (the gate oxide) and are used to modulate the passage ofcurrent 102 through the channel region 116 to the source electrode 118,which is in electrical communication with the power management module'sprimary inductor coil.

The “On” resistance is a critical operational parameter of all powerFETs, since higher resistivity generates more heat, which, if notproperly managed, will produce higher temperatures in the channel regionthat will degrade transistor performance. The On resistance (R_(ON)) ofa standard power FET is the sum of the channel resistance (R_(Ch)) andthe drain resistance (R_(Drain)) and is mathematically characterizedusing:

$\begin{matrix}{R_{ON} = {{\underset{\_}{R}}_{\underset{\_}{Ch}} + {\underset{\_}{R}}_{\underset{\_}{Drain}}}} & \left( {1A} \right) \\{\mspace{45mu} {= {\frac{L_{gate}}{W_{gate}C_{gate}{\mu_{elec}\left( {V_{G} - V_{{GS}{({sh})}}} \right)}} + {k\; \rho_{Drain}}}}} & \left( {1B} \right)\end{matrix}$

Where,

-   -   L_(gate) is gate length,    -   W_(gate) is the gate width,    -   C_(gate) is the gate capacitance,    -   μ_(elec) is the electron mobility of the semiconductor layer        104,    -   V_(G) and V_(GS(sh)) are the gate and short-circuited        gate-source voltages, respectively,    -   k is a geometrical factor related to the source electrode        geometry,    -   and,

ρ_(Drain) is resistivity of the semiconductor drain comprising layers304 and 306.

The gate length L_(gate), when viewed in cross-section, is the width ofthe gate electrode 112 as depicted in FIG. 5A. Similarly, the gatewidth, W_(gate) would extend above and below the plane in thecross-sectional view provided in FIG. 5A, and is the sum total length ofthe active gate electrode 502 depicted in FIG. 5C.

FIG. 5B depicts a top perspective view of a power management module witha vertical FET 150 configured for operation as a flyback DC-DC convertercircuit 1. The present invention is not restricted to flyback converterconfigurations and may be used to construct additional DC-DC convertercircuits known to practitioners skilled in the art of power managementusing the methods and embodiments instructed herein. These methods andembodiments are also useful in constructing other power managementdevices, such as AC-DC/DC-AC inverters or AC-AC transformers, which aresimilarly benefited by the invention and considered to be additionalembodiments.

The physical design (top perspective) depicted in FIG. 5B consists ofthe electrically patterned n-type semiconductor layer 152 (104 incross-sectional view) in which active power FET(s) and diode(s) may belocated. The switch controller unit 154 may also be embedded in thesemiconductor substrate or it may alternatively be mounted as anadditional chip on the surface of the n-type semiconductor layer 152.One or more additional ground contact pads 156 and 157, with one groundcontact pad 156 applied to the top surface to establish a ground controlcircuit connection 158 to the switch controller unit 154 or to thebottom electrode of output capacitor 160, which may be anultra-capacitor. A gate control circuit connection 162 is made to theinsulated transistor gate (not shown in FIG. 5B), which is buriedbeneath the source electrode 164 (118 when viewed in cross-section asshown in FIG. 5A). The insulated transistor gate modulates current drawnfrom the underside ground contact 157 to the source electrode 164,through the vertical power FET 100, which supplies the drawn current tothe primary coil of a toroidal transformer 165 formed around a magneticcore 166. The primary inductor coil of the toroidal transformer 165 iselectrically connected to the source electrode 164 at the primary coilinput 167 and to an input power contact pad 168 at the primary coiloutput 169. The input power contact pad 168 is in electricalcommunication with an outside power source. The secondary coil's output170 is in electrical communication with a circumferential electrode 171that partially surrounds the toroidal transformer 165 and is inelectrical communication with the input of a diode (p-n junction) 172buried in the n-type semiconductor layer 152. An additionalcircumferential electrode 174 that partially encompasses the toroidaltransformer 165 is in simultaneous electrical communication with theoutput of the diode (p-n junction) 172 and the module output pad 176that supplies conditioned power current to the load. The input 177 (notshown) to the secondary coil is located on the opposing side of thetoroidal transformer 165. It is in electrical communication with thebottom electrode of the output capacitor 160, which is also incommunication with electrical ground through ground contract pad 156.The top electrode of the output capacitor 160 is in electricalcommunication with the output pad 176. An output control circuitconnection 178 is made to the top electrode of the output capacitor 160.The control circuit connection 178 may be made, as is most convenient,directly to the output pad 178, or to the additional circumferentialelectrode 174 in electrical communication with output of the diode 172or to the output electrode of the output capacitor 160 as they are allin electrical communication with one another. A power input controlcircuit connection 179 is made between the switch controller unit 154and the power input contact pad 168. It is herein also implied thatother control circuitry may be added to the fully integrated circuitmodule that would add greater processor functionality and requireadditional electrical traces to maintain proper electricalcommunication.

A specific embodiment of the present invention is to mitigate heatgenerated by the device by using a large three-dimensional structure toreduce R_(ON) with a properly configured gate electrode. FIG. 5Cprovides a magnified top perspective view of a fully integrated powermanagement module with the source electrode 164 removed to expose aserpentine FET gate electrode 180 that has an elongated gate width woundcircumferentially on the region of the n-type semiconductor layer 152located within the “donut hole” of the toroidal transformer 165. Theinsulated gate electrode is naturally formed over matching patterneddoping profiles implanted or diffused into the semiconductor substrateto reproduce the electronic profile patterned defined in FIG. 5A (whenviewed in cross-section) throughout the entire region over which theinsulated gate electrode is overlaid. Each circumferential winding orloop of the gate electrode is electrically connected to the next innercircumferential gate electrode interior.

This model representation of the present invention depicts an FET gateelectrode that has a 100 μm gate length (L_(gate)) and a 1 meter widegate width (W_(gate)) to make it easier to visualize pictorially. Itcould just as easily comprise an FET gate electrode that a 1 μm long (orsmaller) gate length (L_(gate)) and a 50 meter wide (or wider) gatewidth (W_(gate)) within the same surface area. A specific embodiment ofthe invention is to establish a gate electrode structure wherein thegate width (W_(gate)) is at least two orders of magnitude, preferablymore than 6 orders of magnitude, greater than the gate length(L_(gate)). i.e., 10²≦W_(gate)/L_(gate), preferably10⁶≦W_(gate)/L_(gate), The gate electrode is in electrical communicationwith the gate control circuit connection 182, which, preferably is aground shielded trace. A larger feed electrode 184 is used to connectthe source electrode 164 to the primary inductor coil of the toroidaltransformer 165. The feed electrode may comprise varying thicknesses andgeometries, such as a ring, to improve current handling characteristics.

Making reference to equations 1A & 1B, it is quite evident that the gategeometry described by the present invention enables a substantialreduction in “On Resistance” (R_(ON)) by reducing its channel resistance(R_(Ch)) component, which is inversely proportional to the ratioW_(gate)/L_(gate). For example, a gate geometry whereinW_(gate)/L_(gate) is 10⁶ will have 1 1/millionth the channel resistanceof a gate electrode where W_(gate)/L_(gate)=1. There are correspondingreductions in the drain resistance R_(Drain), since the geometricalfactor, k, for the source electrode 164 is the ratio of the thickness ofthe high resistivity n-type semiconductor layer 104 to the surface areaof the source electrode 164. The source electrode 164 depicted does notnecessarily have to have a hole in its center as depicted in FIG. 5B.When there is a donut hole at its center, the source electrode's totalsurface area is determined as the area spanned by the outer radius minusthe area spanned by the inner radius, or:

A=π(R _(out) ² −R _(in) ²)  (2)

where, R_(in)=0 when there is no hole at the center. Ordinarily, thethickness of the n-type semiconductor layer 104 (152) is 5 μm (5×10⁻⁴cm) or less. When the source electrode has an outer radius on the orderof 1 cm with an inner radius of 0.4 cm, the total surface area of thedonut is 2.51 cm² making the geometrical factor k=2×10⁻⁴, assuming asemiconductor layer 104 thickness of 5 μm. In designs where the layerthickness can be reduced to 2 μm and the source electrode is expanded to2 cm radius with no donut hole, the geometrical factor becomesk=1.6×10⁻⁵.

The greatly expanded size of the source electrode 164 lowers heatgenerated by the power FET by lowering its On Resistance (R_(ON)) byorders of magnitude. The elongated gate width also increases gatecapacitance (C_(gate)), which also reduces R_(ON), but sharply lowersgate switching speeds. A lower switching speed can be alleviated bydesigning the elongated gate structure as a transmission line andconfiguring the serpentine FET gate electrode 180 to be resonant at aparticular frequency of interest. A given segment of the serpentine FETgate electrode 180 contains a capacitive element, determined by thecharge that is collected beneath the gate, a resistive elementdetermined by the thickness, length and cross-sectional area of theconductor used to form the serpentine FET gate electrode 180, and aninductive element formed by half-turns 186 that loop the serpentinewinding back upon itself. Any serpentine pattern can be distributedwithin the volume of the source electrode, though it is preferred toconfigure the serpentine pattern in a manner that produces a resonantFET gate electrode 190 that has a characteristic resonance (ω_(o))defined by a transmission line per unit length internal capacitance (C)192, and inductance (L) 194,

ω_(o)=2πƒ_(o)=1/√(LC)  (2)

as shown in FIG. 5D. Methods that utilize LCD techniques to construct a“resonant transistor gate” from an elongated gate structure thatincorporates tight tolerance passive components within the gatestructure are instructed in de Rochemont '894 copending with thisapplication.

As shown in FIG. 6, certain vertical FET architectures allow differentcurrent densities to be switched through the circuit. In general,double-diffused power FET (DDMOSFET) architectures 200 achieve thelowest current densities, bipolar transistors 202 achieve higher currentdensities, and insulated gate bipolar transistors (IGBT) 204 provide thehighest current densities. Therefore, the current load objectives areused to determine which type of FET architecture should be integratedinto the monolithic power management module with a vertical FET 150.Bipolar 202 and DMOSFET 200 architectures are suitable for lowerinstantaneous current loads, say less than 50 A, whereas IGBTarchitectures are preferred for higher instantaneous current loads. FIG.5E depicts an alternative A-A′ cross-sectional view of a monolithicpower management module with IGBT vertical FET 220; which may optionallyinclude a substrate 222 and electrode 224 that functions as ground and aheat sink. LCD enables the insertion of a very thin amorphous layer 226that allows a single crystal p⁺-type semiconductor drain layer 228 to bedeposited upon the drain electrode 224. A p-n junction 230 forms betweenthe semiconductor drain layer 228 and an n-type semiconductor layer 232.The n-type semiconductor layer 232 is electrically patterned with p-typesubchannel 234A,234B,234C and n+-type dopant profiles236A,236B,236C,236D that are in electrical communication with the sourceelectrode 238. The insulated gate electrode 240 modulates inversioncarrier populations in a channel 242 that allow currents to flow fromthe drain 228 to the source electrode 238. The gate electrode 240 isencapsulated within a low loss high-dielectric breakdown insulatingmaterial 242A,242B, preferably an amorphous silica insulating material.

Power FET switching speed is generally limited to clock frequencies wellbelow 1 GHz, more typically these switching speeds are constrained toclock frequencies well below 500 MHz. Lower switching speeds are aparticular problem with IGBT power FETs because the additional p-njunction adds additional recombination currents. Lower switching speedsrequire larger inductor and capacitor elements to be added to the powermanagement circuit, which comprises size and economic value. These lowswitching speeds are constrained by the electron mobility in silicon(μ_(elec)=1,300 cm²-V⁻¹sec¹) and are the principal cause of inadequatememory management that is the principal cause for underutilizedmicroprocessor capacities. It is therefore a principal embodiment ofthis invention to integrate power FET devices into the chip carrier thatsimultaneously reduce thermal management issues and increase switchingspeeds to levels that substantially improve localized high-speedcomputing. This is achieved through LCD technology's ability tointegrate mismatched materials into a functional device by substitutingsemiconductor materials that have higher electron mobility μ_(elec) intoany of the semiconductor layers 104,106,228,232. Improved electronmobility not only serves to reduce R_(Ch) to relieve thermal managementissues and stabilize junction dynamics under high operational currentloads, it also increases recombination currents in the channel region toincrease overall switching speeds.

Therefore, it is desirable to utilize semiconductors, such as silicongermanium (SiGe), germanium (Ge), gallium arsenide (GaAs), galliumnitride or other III-V compound semiconductors, or when the applicationwarrants, II-VI compound semiconductors, which have higher electronmobility or better thermal properties than silicon (Si). In particular,it is preferred embodiment of the present invention to use the III-Vcompound semiconductor indium-antimonide (InSb) which has an electronmobility μ_(elec)=77,000 cm²-V⁻¹ sec⁻¹ in the deposited transistorstructure. Compound semiconductors exhibiting such high carrier mobilitytypically have narrow energy band gaps and require the FET structure tobe configured in such a way to form either 2-dimensional (2D) electrongas using layered structures or a three-dimensional (3D) electron gas asinstructed in de Rochemont '846.

A particular aspect of the invention integrates the monolithic powermanagement module modulated by a vertical FET 300 on a semiconductorsubstrate 302 as shown in FIGS. 7A,7B,7C,7D,7E. It includes a toroidaltransformer 304 with interleaved mechanically reinforced coil windings,wherein two or more segments of either the primary or the secondary coilare wound in parallel, a plurality of semiconductor layers 306,308,ground electrodes 310,312, a parallel plate capacitor 314, a diode 316,a switch controller unit 318, a power input pad 320, a power output pad322, and additional circuitry 324 consisting of passive and activecomponents. Although the additional circuitry 324 is shown forillustrative purposes in FIG. 7A as feeding the switch input electrode326 to the resonant gate vertical power FET 327 (not visible in FIG. 7A)that modulates current to the source electrode 328 in electrical contactwith the primary inductor coil of the toroidal transformer, theadditional circuitry 324 may be used to serve any function and locatedon any layer surface in the power management module 300 or thesemiconductor substrate 302.

Two or more parallel winding segments permit the construction of atransformer having arbitrary turn-ratios, as well as low proximity andflux leakage losses made possible by the consistent spacing betweenwindings of the primary and secondary coils. Two or more parallelwinding segments are inserted into the primary coil when a step-uptransformer is desired. Conversely, two or more parallel windingsegments are inserted into the secondary coil when a step-downtransformer is desired. FIGS. 7B,7C illustrate a monolithic modulehaving a 10:1 step-down transformer constructed using the methodsdisclosed in de Rochemont '222. The primary coil windings 330 areconfigured as 20 turns wound in series by first depositing the bottomwinding conductor segments on the surface of the n-type semiconductorlayer 302. The secondary coil windings 332 are configured as two 10-turnwinding segments, with each winding segment having 10 turns wound inparallel. The parallel turns are achieved by terminating the individualparallel winding on upper 334 and lower 336 outer ring conductors, whichare electrically insulated from one another by an insulating dielectricmaterial 338 (not shown), preferably an amorphous silica insulatingdielectric. Parallel winding terminations 340 that electrically contactthe upper outer ring conductor 334 to the lower outer ring conductor 336are located at the secondary coil input 342 and output 344 and thebeginning or ending of a parallel-turn segment. In this configuration,the two parallel turn segments are connected in series by electricalconnection through the lower ring conductor 336. The secondary coilinput 342 is in electrical communication with the bottom electrode 346of the parallel plate capacitor 314 and the ground pad 310. The topelectrode 348 of the parallel plate capacitor 314 is in electricalcommunication with the power output pad 322.

LCD methods are used to construct the additional circuitry 324 byselectively depositing metal and dielectric material that form thepassive or active component. Using these techniques and referring toFIG. 7D, the circuit diagram 349 in FIG. 7E is replicated on thesemiconductor substrate 302 by selectively depositing resistivedielectric material to form resistors 350A,350B,350C. Capacitors352A,352B may be formed by depositing capacitive dielectric 353A betweenparallel electrodes 354A,354B in vertical fashion, or by selectivelydepositing capacitive dielectric 353B within inter-digitated electrodes356A,356B. Active devices, such as diodes, are formed by selectivelydepositing electrodes to make contact with the inputs and outputs of anelectronically doped region 358 of the semiconductor substrate 302.

A further aspect of this invention relates to the integration of atleast one inductor or transformer coil enveloped around a low-loss (≦0.5mW-cm⁻³), high permeability (μ_(R≧)70) magnetic core material that isfully integrated on to a semiconductor layer. Fully integrated systemsachieve dramatically higher field reliability and sharply lower cost.While transistor assemblies have been integrated into semiconductor die,the inability for powder-based or paste-based ceramic manufacturing tomaintain performance values within “critical tolerances” has madesystem-on-chip passive assemblies cost prohibitive due to the inabilityto rework an out-of-tolerance passive component once it is integratedinto a solid state structure.

LCD alleviates these concerns through its ability to selectively depositcompositionally complex electroceramics that have atomic scale chemicaluniformity and nanoscale microstructure controls. This enables theconstruction of circuitry that meets critical performance tolerances bymaintaining dielectric values of the embedded passive components within≦±1% of design specifications over standard operating temperatures. Thecombination of atomic scale chemical uniformity and nanoscalemicrostructure are strictly required when inserting a high permittivity(∈_(R≧)10) electro ceramics. As shown in FIG. 8A, the dielectricconstant of the barium strontium titanate ceramic remains stable overstandard operating temperatures when its average grain size is less than50 nanometer (nm) 360, but will vary by ±15% when the average grain sizeis 100 nm 361 and by ±40% when the average grain size is 200 nm 362.FIG. 8B depicts the initial permeability of amagnesium-copper-zinc-ferrite dielectric as a function of temperaturefor five different compositions, wherein the concentration of copper(Cu) is substituted for magnesium (Mg) according to the compositionalformula Mg_((0.60-x))Cu_((x))Zn_((0.40))Fe₂O₄, with x=1 mol % 370, x=4mol % 371, x=8 mol % 372, x=12 mol % 373, and x=14 mol % 374. Invariancein the permeability of magnetic materials is generally achieved inchemically complex compositions, and then only over narrow or specificcompositional ranges, such as for x=1 mol % 370 and x=8 mol % 372 in theMg_((0.60-x))Cu_((x))Zn_((0.40))Fe₂O₄ system. Although permeability is afunction of microstructure, grain size has a more pronounced effect onloss. However, the atomic scale chemical uniformity and compositionalprecision of LCD methods is needed to maintain “critical tolerances” inthe monolithic assembly over standard operating temperatures.

In another aspect the present invention integrates monolithic powermanagement modules and additional circuitry onto a semiconductor chipcarrier to reduce power consumption and improve the utilization ofmulti-core processors used in computing and RF radio systems. FIG. 9depicts a chip carrier 400 that holds a plurality of semiconductor die402A, 402B, 402C, 402D, 402A′, 402B′, 402C′, 402D′ surface mounted on asemiconductor substrate 404. The semiconductor die may be mounted instacks 402A′, 402B′, 402C′, or configured as single die 402D′. At leastone monolithic power management module 406 is co-located on the chipcarrier surface. The monolithic power management module 406 may containsurface FET, but preferably contains a vertical FET with a resonantgate, as described above, to switch high current levels (≧50 A) at highspeeds (≧100 MHz). The chip carrier 400 is used to deliver power to thevarious semiconductor die through power lines 410 and surface groundtraces 412, and also has signal interconnects (not shown for clarity) toroute data and control instructions between the various semiconductordie 402A, 402B, 402C, 402D, 402A′, 402B′, 402C′, 402D′. The chip carrier400 may additionally contain a variety of other low-level sensing,latching and bus circuitry (not shown for clarity) integrated on or intoits surface, as well as additional circuitry assembled from passivecomponents that have functional values that vary less than ±1% fromtheir specified performance value over standard operating temperatures.

An additional aspect of the invention utilizes LCD methods to produceclock circuitry 414 that remains stable with temperature. The clockcircuitry consists of a high-Q LCR resonator, where the self-resonancefrequency is determined by the capacitance that develops between thewindings of an inductor coil 416 mounted on an amorphous silica block418 to minimize dielectric losses within the clock. It is alsoconceivable that the capacitance of the LCR resonator is derived fromadditional capacitive elements (not shown) that may comprise a phasedlocked loop array mounted on or embedded within the carrier'ssemiconductor substrate 404. The clock timing may be altered byintegrating a switching element 420 into semiconductor chip carriersubstrate 400 that provides the option to change the high-Q resonator'sself-resonance frequency by routing the timing signal through differentturns of the inductor coil 416.

Reference is now made to FIGS. 10A,10B,11A,11B to illustrate a finalembodiment of the invention that utilizes the tight tolerance passivecircuitry monolithically integrated into the chip carrier 400 to reducetransistor counts, form factor, power consumption, and cost ofsemiconductor die 402A, 402B, 402C, 402D, 402A′, 402B′, 402C′, 402D′surface mounted on the chip carrier's semiconductor substrate 404.Passive components, and filtering networks formed with them, are used totune signal frequencies. Passive networks created from components thathave loose tolerances, (performance values vary ≧±5%), requireintegrated circuit (IC) designers to design semiconductor die thataccommodate all potential variations generated in the signals tuned bythe loose tolerance components. This is done by breaking all anticipatedtuning (amplitude and frequency/phase characteristics) of the processedsignal into a bell curve 500, similar to that shown in FIG. 10A. Thecurve is broken up into performance segments 502,504,506,508,510,512,514that dedicate transistor banks, or “buckets”, that are specificallydesigned to allow the die to process signals falling into any one of theanticipated tunings defined by segments 502,504,506,508,510,512,514.This causes a large number of redundant transistor assemblies520,522,524,526,528,530,532 to be integrated into the semiconductor die534, adding cost, size, wasted power to the circuit, as shown in FIG.10B.

As illustrated in FIGS. 11A,11B, the ability to integrate tighttolerance passive components, (performance values vary ≦±1%), into thechip carrier 400, eliminates this uncertainty, reducing the numberperformance segments 600 that need to be considered in the statisticaldistribution 602 of potential design tolerances. This aspect of theinvention results in a significant reduction in the number of transistorbanks or “buckets” 612 that need to be integrated into the semiconductordie 610, resulting a in a less sophisticated smaller form-factor, lowercost semiconductor when they can be integrated into fully integratedsilicon chip carrier.

The present invention is illustratively described above in reference tothe disclosed embodiments. Various modifications and changes may be madeto the disclosed embodiments by persons skilled in the art withoutdeparting from the scope of the present invention as defined in theappended claims.

1. A monolithic power switch, comprising: a semiconductor layer; a threedimensional FET formed in the semiconductor layer to modulate currentsthrough the semiconductor layer; and a toroidal inductor with a ceramicmagnetic core formed on the semiconductor layer around the FET andhaving a first winding connected to the FET.
 2. The switch of claim 1,further comprising a semiconductor carrier having the switch formedtherein.
 3. The switch of claim 2, wherein the semiconductor carrierincludes passive ceramic components formed thereon and electricallyconnected to the switch.
 4. The switch of claim 2, further comprising: adiode formed in the semiconductor layer peripherally to the toroidalinductor and connected to rectify current from the inductor; and acapacitor having a ceramic dielectric formed on the semiconductor layer,and connected to the diode.
 5. The switch of claim 2, further comprisinga timing oscillator formed on the carrier and comprising an oscillatorcoil formed on an amorphous silica layer, wherein the oscillator coilholds its inductance value to within 1% over a normal operatingtemperature range.
 6. The switch of claim 5, wherein the timingoscillator includes switching elements formed in the carrier forcontrolling oscillation frequency of the oscillator coil.
 7. The switchof claim 1, wherein the FET is a double-diffused MOSFET or an insulatedgate bipolar transistor.
 8. The switch of claim 1, wherein the FETincludes a gate electrode having a gate width to gate length ratio thatis equal to or exceeds 100, or alternatively 10⁶.
 9. The switch of claim1, wherein the FET includes an elongated gate electrode that forms aresonant transmission line.
 10. The switch of claim 9, wherein theelongated gate electrode meanders over an area of the substrate locatedwithin a central opening of the toroidal inductor.
 11. A semiconductorpower switch, comprising: a planar first electrode; a first layer dopedsemiconductor material disposed on the first electrode that forms ohmiccontact with the planar first electrode; a second layer of dopedsemiconductor material disposed on the first layer that iselectronically patterned to form a double-diffused MOSFET; a secondelectrode disposed upon the second layer; an elongated gate electrodelocated to modulate current flow from the planar first electrode throughthe second layer to the second electrode and having a ratio of gatewidth to gate length that this greater than or equal to 100; wherein theelongated gate electrode forms a serpentine pattern over the secondlayer and is insulated from the second region and the second electrode;and wherein the elongated gate structure forms a transmission line thatis resonant at a predetermined power switching frequency.
 12. The switchof claim 11, further comprising a circuit module having the switch ofclaim 1 formed therein.
 13. The switch of claim 12, wherein theelongated gate electrode is meandered adjacent a contiguous surface areaof the second layer to maximize gate width over that contiguous surfacearea.
 14. The switch of claim 13, wherein the first layer is formed as aregion of the substrate and the contiguous surface area is surrounded bya toroidal inductor having a ceramic core formed on the substrate. 15.The switch of claim 13, wherein the elongated gate electrode includesadjacent parallel gate portions.
 16. The switch of claim 11, wherein thedouble-diffused MOSFET includes a pair of parallel elongated channelregions located beneath the elongated gate electrode.
 17. The switch ofclaim 16, wherein the elongated gate electrode is meandered and has agate width to gate length ratio that is greater than or equal to 10⁶.18. The switch of claim 11, wherein the first semiconductor layer isdoped to form an insulated gate bipolar transistor when makingelectrical contact with the second semiconductor layer.
 19. A monolithicpower management module, comprising: a semiconductor carrier; a threedimensional FET formed in the semiconductor carrier to modulate currentsthrough the semiconductor carrier; and a toroidal inductor with aceramic magnetic core formed on the semiconductor carrier around the FETand having a first winding connected to the FET.
 20. The module of claim19, a plurality of active components and passive ceramic componentsformed on or in the semiconductor carrier.